As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETURNED TO FIELD WITH SMOKE REPORTED IN CABIN BY F/A. CREW AND PAX REPORTED SMOKE COMING FROM LOWER AND UPPER AIR VENTS. RAN PACKS FOR AN EXTENDED PERIOD USING ENGINES AND APU AS A BLEED SOURCE. NO DEFECTS NOTED. SUSPECT DE-ICE FLUID CONTAMINATION.